How Sitemap is important?

I would like to know about sitemap. How sitemap is important in SEO and how to create it?

You have many online free tools to create sitemap. Sitemap is useful in getting your page indexed faster. You need to add your sitemap in Google webmaster tools to check if any of your page is not reachable

ya, because sitemap is the get backlink and all pages crawler in one time.

Sitemap as name suggest it's a map of your website which includes links of all website pages there are two types of sitemap one is HTML sitemap and the other is XML sitemap. HTML sitemap is generated for users through which users can easily navigate throughout the whole website pages, XML sitemap is for search engines which helps the search engine's crawlers to easily go throughout whole website pages , you can submit your XML sitemap in Google webmaster tool which helps to index your website URLs in Google search engines.